Relationship Between Nitrous Oxide Emission And Soil Nitrogen Accumulation From Greenhouse Vegetable Fields In Beijing By Different Measures Of N

【Object】Since the 20 th century, with the growth of population, people continue to demand for vegetable growing, Vegetable acreage will maintain sustained growth.. Greenhouses because of their different environments and field production, coupled with a high nitrogen fertilizer inputs. It is easy to produce due to a series of problems caused by excessive nitrogen fertilizer, such as the accumulation of nitrogen problem, ammonia volatilization and yang emissions, and low nitrogen utilization. Among them, the N2 O emissions and soil nitrate accumulation problem is most prominent. These two questions is less one systematic observation in greenhouse. In order to provide a reasonable measure, not only economic interests, but also to safeguard the ecological environment, N2 O fluxes in conjunction with the main environmental drivers(tomato-cabbage) were observed from Feb. 2014 to Dec. 2014.【Methods】In this study, there are five treatments, four treatments. Farmer conventional fertilization(FP)、decrease of nitrogen(N) fertilization(OPT)、the combination of decrease of nitrogen(N) fertilization and Straw(OPTS)、the combination of decrease of nitrogen(N) fertilization and nitrification inhibitor(OPTD)、control(CK), were implemented in a typical greenhouse vegetable fields in Beijing suburbs to test the impacts of N2 O emissions and Soil nitrogen accumulation.【Results and conclusion】The main results were showed as follows:(1) Clear the growing season and rotation period characteristics of N2 O emission fluxes from greenhouse vegetables fields. The N2 O emission peaks were short lived and fluctuated largely and the highest emissions occurred during the 3-6 days period just after fertilization and irrigation while 7-10 days period after basal fertilization. Compared to the FP treatment, the OPT、OPTS and OPTD treatments both reduced the cumulative N2 O emissions with 44.93%,49.38% and 63.78%(P<0.05), respectively. In conclusion,three descreased N measures could effectively reduce the N2 O emissions from the greenhouse vegetable field, the effect of emission reduction expressed as: OPTD>OPTS>OPT. The emission factors(EFs) from different treatments ranged from 0.29-0.74%, lower than the IPCC default 1%.(2) Determine the factors affecting N2 O emissions preliminary. There is a consistent trend from the N2 O fluxes and inorganic nitrogen content. During the tomato growing season, the N2 O fluxes were significantly correlated with the soil water filled pore space(WFPS) for all the treatments. During the cabbage growing season, the N2 O fluxes were significantly correlated with soil temperature. Soil water filled pore space(WFPS) was the main environment factors influencing N2 O emissions in spring and summer, Soil temperature was the main environment factors influencing N2 O emissions in autumn season.(3) Field experiment was carried out to study the effects of different treatments of NO3--N accumulation in planting pattern of tomato-cabbage, the study showed that OPT treatment can decreased the NO3--N accumulation addition in 0-20 cm soil layer. NO3--N accumulation increased in 0-20 cm soil layers of OPT,OPTS, OPTD were 19.05 kg hm-2,191.05 kg hm-2,55.56 kg hm-2; NO3--N accumulation decreased in0-20 cm soil layers of OPT,OPTD were 45.47 kg hm-2,69.15 kg hm-2 respectively. There is a rapid increased in the soil nitrate accumulation in high temperature sealed greenhouses. The highest nitrate content is in surface soil. Deeper soil layers caused little accumulation of NO3--N with in the 0~100 cm soil profile. Still maintain a high level in 80-100cm; In 0-100 cm soil layer, there are more than 50% of the total nitrate accumulation in 40 cm soil layer below, indicating the presence of high-risk facilities vegetable nitrogen leaching.【Conclusion】Compared to the FP treatment, there was no significant difference with three decreased N measures. Comprehensively considering the vegetables yields, N2 O emissions and nitrogen accumulations,decrease of nitrogen(N) fertilization and nitrification inhibitor(OPTD) treatment is better than other descreased N treatment, can effectively reduce the N2 O emissions and nitrate accumulations in 0-100 cm soil in greenhouse vegetables field. It will be worthy in production practices.